Abstract: Analyzed via relevant model are development and formation of wall eccentricity of the seamless steel tube. And also elaborated is a method for reducing error of such eccentricity，i.e.，the in-piercing process eccentric high frequency spinning technique. This method is used to monitor the manufacturing process. The analysis reveals that the said pipe eccentricity is originated by the bloom eccentricity and the piercer plug eccentricity. The superposition of these two factors lead to the local maximum value. Owing to using the said eccentric HF spinning technique during piercing operation，the vibration amplitude that causes the eccentricity is reduced to get circumferential metal flow of the workpiece so as to lessen the wall eccentricity of the pipe.